\begin{table}[htbp]\centering
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\caption{Child mortality at the child level}
\begin{tabular}{l*{3}{c}}
\toprule
                    &\multicolumn{1}{c}{(1)}&\multicolumn{1}{c}{(2)}&\multicolumn{1}{c}{(3)}\\
                    &\multicolumn{1}{c}{\textbf{\begin{tabular}[c]{@{}c@{}}0-5 years old\end{tabular}}}&\multicolumn{1}{c}{\textbf{\begin{tabular}[c]{@{}c@{}}0-1 year old\end{tabular}}}&\multicolumn{1}{c}{\textbf{\begin{tabular}[c]{@{}c@{}}1-5 years old\end{tabular}}}\\
\midrule
Full treatment      &       1.059   &       1.120   &       0.612   \\
                    &     (0.239)   &     (0.295)   &     (0.286)   \\
\midrule
N                   &      10,118   &       4,543   &       8,635   \\
Adjusted p-value (FT)&       0.900   &       0.515   &       0.450   \\
\bottomrule
\end{tabular}
\end{table}
